1. Field of the Invention
The invention relates to a process for telomerizing olefins, especially dienes, with a telomerizing compound containing at least one mobile hydrogen atom, particularly to a process wherein the amount of the diene is at least equivalent to the amount of mobile hydrogen atoms.
2. Description of the Prior Art
The French Pat. No. 2,045,369 discloses a process for preparing diolefinic alcohols containing twice the number of carbon atoms of the starting 1,3-diolefins. According to this process, a reaction mixture is formed containing the diolefin, water, and a solvent wherein the diolefin, as well as the water are at least partially soluble in the presence of a catalyst containing palladium or platinum, phosphine and carbon dioxide gas as a co-catalyst. The diolefinic alcohol is formed by the reaction of the diolefin with water. For use in this type of process, such solvents are selected which have a certain affinity for the diene and for the water in order to maintain a liquid and homogeneous reaction mixture. The solvents which are used are organic solvents such as, e.g., dioxane, dimethyl acetamide, tert. butanol and acetone.
Processes for telomerizing diolefins, particularly butadiene, with various compounds containing mobile hydrogen atoms, such as alcohols, carbocyclic acids, silanols, ammonia, amines, compounds with reactive methylene groups, and the like, in the presence of a catalyst usually containing palladium and a co-catalyst, such as phosphine, are known in the art [see Accounts Chem. Res., 1973, 6(1) 8-15].
The first major problem which arises during carrying out the prior art processes is the separation of the reaction products and the catalyst. It is, in effect, desirable to recover the catalyst for re-utilization. Yet the prior art proposes only processes wherein the final separation step has never been satisfactorily solved by a generally applicable method. It proves always to be difficult and incomplete. In effect, in most of the cases, not all of the reaction products can be separated from the reaction medium by simple methods since on the one hand, the catalyst is soluble in the organic solvents which are used and on the other hand, certain by-products are too non-volatile to be separated by distillation. If it is possible to separate the main reaction product by distillation, for reasons concerning the thermal stability of the catalyst, it is impossible to eliminate the by-products, such as, oligomers and telomers of the diolefin, by distillation.
According to the prior art processes, a loss in catalyst is noted and the latter is present in the reaction product.
In case the compound containing the mobile hydrogen atom is water, the second major problem is how to exalt its reactivity. The solutions provided by the prior art exist in, e.g., adding an alcohol to the reaction mixture (British Pat. No. 1,354,507 and U.S. Pat. No. 3,670,032). A large amount of carbon dioxide gas has been used to increase the reaction speed (French Pat. No. 2,045,369, cited above). In the first case, the major inconvenience is the joint formation of undesirable ether (often even as the major product). In the second case, the amount of carbon dioxide has to be continuously recycled for economical reasons. Furthermore, the separation problems outlined above remain.